Detection of drugs after consumption is useful for many purposes including detection of illicit drug use, verification of prescription drug consumption, detection of drug consumption to avoid potential interference from contraindicated drugs, monitoring pharmacokinetic rates, dosage adjustment and many others. Drug testing typically involves urine or blood sampling, and in some cases saliva testing. In some situations a quantitative measurement is needed while in others, a qualitative presence detection is sufficient.
Drugs may be detected in an individual's bodily fluids or bodily waste by several methods. These include colorimetric assays, immunoassays, chromatography, and other chemical detection methods. Each of these methods is associated with its own limitations.
Convenient methods of drug detection and quantification include detection of the drug or drug metabolite in urine or saliva. However, detection and measurement of a drug by colorimetric or immunoassay methods typically requires development of a custom assay for each chemical or biochemical target. This means that a detection assay must be developed specifically for each drug or class of drugs. Developing a custom assay limits drug detection to high risk drugs of abuse or very common drugs for which a large enough market exists. More specifically, the need for the assay must be worth the cost of developing the assay. Alternatively, separation and detection techniques, including chromatography may be used. However, these techniques require complex lab equipment and calibration.
An alternative method to detect and/or quantify the presence of a drug in an individual's body is to put a marker in the drug, the marker having a detectable signature or characteristic. This technique alleviates the need to directly measure the drug or the drug metabolites. With this technique, the problem simplifies to developing methods to detect the marker instead of the drug or drug metabolite. Because there are many available drugs, many different markers are needed for to distinguish between different drugs. The markers may have one or more distinguishing characteristic so that the identity of each drug may be determined and the simultaneous presence of multiple drugs may be detected. Ideally, the markers may be biocompatible and not significantly biodegradable. They may have an easily detected signature and not interfere with the efficacy of medically useful drugs. For convenience, the markers may be cleared from the body through urine. Markers that meet these specifications and a device to conveniently identify and quantify the markers in urine is needed.